JP2001042387A - Focal plane shutter for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focal plane shutter for a camera for preventing the inertial force of a blade group from working on the attracting/holding force of an electromagnet as in the conventional practice when a driving member is stopped once at an exposure operation starting position prior to the exposure operation at photographing. SOLUTION: As for each blade group, arms 13 and 19 are energized so as to be rotated clockwise by an arm spring (not-illustrated). At a setting operation, the blade group never work to the last together with each driving member 4 and 7, and the set state is maintained by bringing the arms 13 and 18 in contact with stoppers 1j and 1k. At photographing, each driving member 4 and 7 works without accompanying each blade group in the case of working from a set position to the exposure operation starting position, so that the inertial force of each blade group never affect the attracting/holding force of the electromagnets 10 and 11 as in the conventional practice when attaching parts 4c and 7c come into contact with the head parts 5c and 8c of iron piece members 5 and 8 so as to stop the driving member once so that the driving member can be suitably stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a leading blade group and a trailing blade group are sequentially operated in the same direction during photographing, and exposure is performed by slits formed by slit forming blades of the two blade groups. And a focal plane shutter for a camera.

[0002]

2. Description of the Related Art In a conventional focal plane shutter of this kind, a front blade group and a rear blade group are operated by a front blade driving member and a rear blade driving member connecting them. Then, those driving members are used during the exposure operation.
By the biasing force of the leading blade drive spring and the trailing blade drive spring, respectively, they are sequentially actuated from the exposure operation start position at predetermined time intervals determined by shooting conditions. The member is adapted to be actuated against the biasing force of those drive springs.

By the way, prior to the start of the exposure operation, there are two types of configurations for holding each of the above-mentioned driving members at the exposure operation start position, such as a locking type and a direct type. However, the present invention relates to a focal plane shutter employing a direct type. As is well known, in the direct type configuration, an iron piece member is attached to each driving member, and immediately before the start of the exposure operation, each iron member is attracted to the respective electromagnet, so that each driving member performs the exposure operation. It is kept at the starting position. For this reason, the structure is easy to make compact as compared with the locking type, but it has various problems in manufacturing, so that various measures are required.

First, when the setting member sets the two driving members, it is impossible to make the two iron pieces contact the respective electromagnets at the same time in the final stage of the operation. . For this reason, in the normal case, each iron piece member is not fixed to each drive member, but is attached with a spring interposed therebetween, until both iron piece members can reliably contact their respective electromagnets.
Both drive members can be activated. Therefore, in the setting completed state, each driving member is in a position where it has been operated more than necessary, and each driving spring is so-called overcharged by that much, and after the contact between the iron piece member and the electromagnet, By tensioning a spring interposed between the iron piece member and the iron piece member, the relative relationship with the iron piece member is changed.

Further, in recent cameras, when photographing is completed, the film is wound up and the shutter is set immediately. In order to prevent the power battery from being wasted, energization of each of the above electromagnets is not performed at the time of setting the shutter, but is performed immediately before the next photographing is performed. Therefore, unlike the locking type in which each driving member is mechanically locked in the setting state, in the case of the direct type, the setting member is immediately moved to the pre-setting position (hereinafter, referred to as the setting position) after the completion of the setting operation. Cannot be returned to the initial position), and is kept at the set completion position until the next photographing is performed.

Then, when the next photographing is performed,
First, each electromagnet is energized to hold each iron piece member by suction, and then the set member is returned to the initial position.After that, the energization to each electromagnet is sequentially stopped, and each drive member is exposed to light. I try to make it. However, when the set member returns to the initial position in this manner, each drive member is interposed between the biasing force of each overcharged drive spring and the iron piece member, and thus, as described above. Due to the biasing force of the tensioned spring, it is slightly actuated from the set position and is prevented from being actuated by the iron piece already attracted by the electromagnet. The position stopped in this way is the exposure operation start position for each drive member.

When each driving member stops at the exposure operation start position in this way, a large impact force acts instantaneously on the iron piece member due to the biasing force of each spring described above. If the attraction force of the electromagnet is not sufficient, each driving member does not stop at the exposure operation start position and runs away with the blade group. For this reason, conventionally, the power supplied to each electromagnet has been considerably increased so that such a phenomenon does not occur. Even with complexity, how to reduce the power supply to each electromagnet has become a major issue. Japanese Patent Application Laid-Open No. 9-304807 and Japanese Patent Application Laid-Open No. 9-304
808 and JP-A-10-48699.

[0008]

However, although the publications described in each of the above publications can be said to be effective to some extent, the structure is relatively complicated, so that the downsizing and cost reduction are primarily intended. It is not very suitable for a camera. Further, when each drive member stops at the exposure operation start position as described above, the force acting on each iron piece member against the attraction force of each electromagnet is only the unique urging force of each spring described above. Instead, the inertial force of the member actuated by it also acts. In particular, the inertial force of the blade group connected to each drive member cannot be ignored. However, conventionally, no proposal has been made to pay attention to the inertial force of such a blade group so as not to be affected by the inertial force.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem. It is an object of the present invention to provide a method in which a driving member reaches an exposure operation start position from a set position prior to an exposure operation. Another object of the present invention is to provide a direct type camera focal plane shutter in which the inertial force of the blade group does not act as a force for separating the iron piece member attracted to the electromagnet from the electromagnet as in the related art.

[0010]

In order to achieve the above object, a focal plane shutter for a camera according to the present invention comprises:
An iron piece member that is attracted and held by the electromagnet is attached.When the set operation is performed, the iron piece member is moved beyond the exposure operation start position to the set position against the urging force of the drive spring, and when photographing, the iron piece member is attracted and held by the electromagnet and then exposed. A drive member that starts to operate by an urging force of the drive spring when the electromagnet is cut off when the electromagnet is de-energized by operating to the operation start position, a plurality of arms pivotally attached to the main plate, and pivotally supported by them. A blade group comprising a plurality of blades, the exposure operation of which is performed by the driving member; and a blade group having a biasing force weaker than that of the drive spring and being hung on the arm to apply the blade group in a set operation direction. An energizing arm spring,
A stopper provided on the main plate and configured to stop the operation of the blade group by the urging force of the arm spring when the driving member reaches at least the exposure operation start position during the set operation. To do. Further, in the focal plane shutter for a camera according to the present invention, the driving pin provided on the driving member is loosely fitted into a hole formed in one of the arms of the blade group, and at the time of the set operation, When the driving member can start the operation of the blade group, the setting operation can be reliably performed without increasing the urging force of the arm spring. Further, in the focal plane shutter for a camera according to the present invention, when the base plate and the stopper are separate members and the stopper is an eccentric pin, it is preferable to adjust the stop position of the blade group during the set operation. Can do it.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to an embodiment shown in FIGS. Note that these drawings are plan views each showing only a substantially left half when viewed from the subject side in a state where the camera is incorporated in a camera. FIG. 1 shows a state immediately after the end of the exposure operation, FIG. 2 shows a state of the set state, and FIG. 3 shows a state after the release and immediately before the start of the exposure operation. . In the description of the configuration, the subject side is referred to as a front side, and the film side is referred to as a back side.

First, the configuration of this embodiment will be described. The shutter base plate 1 has an opening 1a formed in a substantially central portion thereof and having a horizontally long rectangular shape. FIG. 1 shows a part of the left side of the opening 1a. As is well known, an intermediate plate and an auxiliary base plate (not shown) are attached to the rear side of the shutter base plate 1 at a predetermined interval, and a front blade is provided between the shutter base plate 1 and the intermediate plate. A group of blade chambers is formed, and a blade chamber of the rear blade group is formed between the intermediate plate and the auxiliary main plate. Further, an opening similar to the opening 1a is also formed in the intermediate plate and the auxiliary base plate, and the opening is usually overlapped to regulate the exposure opening. Will be described assuming that the shape of the opening 1a regulates the exposure opening.

On the left side of the opening 1a, there are formed two arc-shaped long holes 1b and 1c, and at the upper end thereof, a well-known cushioning member 2 having a C-shaped plane shape. , 3
Is attached. Further, shafts 1d and 1e are erected on the front side of the shutter base plate 1, and shafts 1f, 1g, 1h and 1i are erected on the rear side. Further, on the back side of the shutter base plate 1, there are provided stoppers 1j and 1k having a columnar shape and different lengths from each other. Of the above-mentioned shafts, shaft 1d and shaft 1f, and shaft 1e and shaft 1h
Are concentrically arranged. For this reason, it is often the case that they are usually manufactured as the same member and fixed to the shutter base plate 1. The shaft 1i is clearly shown in FIGS. 2 and 3, and is hidden in FIG. 1 by a mounting portion 7c of a rear blade drive member 7 described later.

A driving member 4 for the leading blade is rotatably mounted on the shaft 1d. The leading blade driving member 4 is made of synthetic resin, has a pushed portion 4a, a driving pin 4b, and a mounting portion 4c, and is driven by a well-known leading blade driving spring (not shown). It is biased to rotate clockwise. The drive pin 4b is provided upright on the back side of the leading blade drive member 4, and
, And has an oval cross section, and its root portion comes into contact with the buffer member 2.

Further, the mounting portion 4c of the driving member 4 for the leading blade is largely raised on the front surface side. In each of the drawings, the mounting portion 4c is cut away to show the inside thereof, in which an iron piece member 5 is mounted with a compression spring 6 interposed. That is, the iron piece member 5 includes an iron piece portion 5a, a shaft portion 5b,
It is composed of a head 5c and is urged by a compression spring 6 so as to protrude the iron piece 5a to the outside. In FIG. 1, the head 5c abuts on the mounting part 4c, thereby The above does not protrude.

A drive member 7 for a rear blade made of a synthetic resin is rotatably mounted on the shaft 1e of the shutter base plate 1. The rear blade drive member 7 has a pushed portion 7a, a drive pin 7b provided on the back side, and a mounting portion 7c formed on the front side, and is a well-known rear part not shown. The blade drive spring is biased to rotate in the counterclockwise direction. The drive pin 7b has an oval cross section and penetrates the long hole 1c of the shutter base plate 1 so that its root can contact the buffer member 3.

The mounting portion 7c is provided with the driving member 4 for the leading blade.
Has substantially the same shape as the mounting portion 4c of
An iron piece member 8 is attached with a compression spring 9 interposed. That is, similarly to the iron piece member 5, the iron piece member 8 is composed of an iron piece portion 8 a, a shaft portion 8 b, and a head portion 8 c, and the compression spring 9 projects the iron piece portion 8 a to the outside. Although energized, in FIG. 1 the head 8c
Abuts on the mounting portion 7c, so that it does not protrude any further.

Further, although a detailed configuration is omitted because it is well known, a support plate is attached to the front surface side of the shutter base plate 1 in parallel with the shutter base plate 1 at a predetermined interval. The supporting plate has an electromagnet 10 for the leading blade.
And the rear-wing electromagnet 11 are attached. In each of the drawings, only the schematic plan shape of the iron core is indicated by an alternate long and short dash line, and is denoted by a reference numeral. And these electromagnets 1
Numerals 0 and 11 are configured to attract the iron pieces 5a and 8a of the iron pieces 5 and 8 when the coils are energized. In addition, a set member for rotating each of the driving members 4 and 7 in a clockwise direction is rotatably mounted on the front side of the shutter base plate 1, but such a configuration is too good. As it is known, it has been omitted for clarity.

Next, the configuration of the front blade group and the rear blade group arranged on the back side of the shutter base plate 1 will be described. First, the front blade group includes two arms 12, 13 rotatably attached to the shafts 1f, 1g of the shutter base plate 1, and four blades 14, 14 pivotally supported in order toward their tips. 1
5, 16 and 17, the blades 17 pivotally supported by the distal ends of the arms 12 and 13 are slit forming blades. And a hole 12a formed in the arm 12.
Is formed larger than in the conventional case, and the drive pin 4b of the drive member 4 for the leading blade is loosely fitted therein. The arm 13 is biased so as to rotate clockwise by an arm spring (not shown) having a biasing force weaker than that of the driving spring for the leading blade, but the arm spring is a torsion coil spring. Then, the coil portion is fitted on the shaft 1g, one arm portion is hooked on the shaft 1i, and the other arm portion is hooked on the hole 13a of the arm 13.

The rear blade group has a structure in which the front blade group is substantially turned upside down, and has two arms rotatably attached to the shafts 1h and 1i of the shutter base plate 1. 18 and 19, and four blades 20, 21, 22, 23 pivotally supported in order toward their tips, and the blade 23 is a slit forming blade. The drive pin 7b of the rear blade drive member 7 is loosely fitted in the large hole 18a formed in the arm 18, and the arm 19 is rotated clockwise by an arm spring (not shown). Being energized. Also,
The arm spring is also a torsion coil spring. The coil portion is fitted on the shaft 1i, one arm portion is hung on the shaft 1g, and the other arm portion is hung on the hole 19a of the arm 19.

Next, the operation of this embodiment will be described. FIG.
Indicates a state immediately after the end of the exposure operation. Accordingly, the driving pin 4b of the leading blade driving member 4 is in contact with the buffer member 2 at the upper end of the elongated hole 1b. At this time, the arms 12, 13 are urged to rotate clockwise by an arm spring (not shown) hooked on the arm 13, so that the edge of the hole 12a of the arm 12 (the left side in FIG. (Edge) is in contact with the drive pin 4b. The four blades 14, 15, 16, 17 of the front blade group are superimposed and stored at a position above the opening 1a.

The driving pin 7b of the rear blade operating member 7
Is in contact with the buffer member 3 at the upper end of the elongated hole 1c. At this time, since the arms 18 and 19 are urged to rotate clockwise by an arm spring (not shown) hooked on the arm 19, the edge of the hole 18a of the arm 18 (the upper edge in FIG. 1). ) Is in contact with the drive pin 7b. Then, the four blades 20, 21, 22, 22 of the rear blade group
Reference numeral 23 is developed to cover the opening 1a.

When the film is wound up in the state shown in FIG. 1, a set member (not shown) rotatably mounted on the front side of the shutter base plate 1
First, the driven portion 4a of the leading blade driving member 4 is pushed, and the leading blade driving member 4 is rotated clockwise against the urging force of the leading blade driving spring (not shown). At this time,
Since the arm 13 is urged to rotate clockwise by the above-described arm spring (not shown), the leading blade group also operates with the arm 12 following the drive pin 4b,
The four blades 14, 15, 16, 17 move downward while reducing the amount of overlap between them.

Thereafter, the slit forming blade 17 of the front blade group
When the overlapping amount of the rear blade group and the slit forming blade 23 reaches a predetermined amount, a set member (not shown) starts pushing the driven portion 7 a of the rear blade driving member 7. Therefore, the rear blade drive member 7 is rotated clockwise against the biasing force of the rear blade drive spring (not shown). At this time, the arm 19 is moved by the arm spring (not shown). As a result, the rear blade group is also operated by the arm 18 following the drive pin 7b, and the four blades 20, 21, 22, and 23 overlap each other. And move downward.

In this way, the set operation of each drive member 4, 7 and each blade group is continued, but in the case of the front blade group and the rear blade group, the set operation of each drive member 4, 7 is performed. The arms 13 and 18 have stoppers 1j and 1k
Stop in contact with. Then, in the stop time, in the case of the leading blade group, the slit forming edge of the slit forming blade 17 has reached a position sufficiently lower than the lower side of the opening 1a (to the extent that there is no fear of bounce or light leakage). From time to time, the exposure operation start position of the leading blade driving member 4 to be described later is started. In the case of the trailing blade group, the slit forming edge of the slit forming blade 27 is sufficiently larger than the lower side of the opening 1a ( From the lower position (without worrying about bouncing)
This is until the exposure operation start position of the rear blade drive member 7 described later.

The driving members 4 and 7 continue the set operation even after the respective blade groups are stopped as described above, but immediately after the respective blade groups are stopped as described above (at the moment when the blades are stopped). The iron pieces 5a and 8a of the iron pieces 5 and 8 may be connected to the electromagnet 1 in succession.
0, 11 and then stop by stopping rotation of the set member (not shown).
FIG. 2 shows a completed state of the set operation thus performed.

Therefore, in the set state shown in FIG. 2, each of the driving members 4 and 7 performs the setting operation even after each of the blade groups is stopped, so that their respective driving pins 4b and 7b
Are separated from the edges of the holes 12a, 18a of the arms 12, 18, and each of the driving members 4, 7 is connected to each of the iron piece members 5, 8,
Since the set operation was performed even after contacting the electromagnets 10 and 11, the iron pieces 5a and 8a of the iron pieces 5 and 8 were compressed by the compression springs 6 and 9 and pushed into the mounting parts 4c and 7c.
The heads 5c, 8c are separated from the mounting portions 4c, 7c. The set member (not shown) does not immediately return to the start position (initial position) of the set operation, but keeps this state until the next photographing is performed.

At the time of the next photographing, when the release button of the camera is pressed, the respective electromagnets 10 and 11 are first energized, and the iron piece members 5 and 8 are held by suction. Next, in order for a set member (not shown) to perform a return operation to the initial position,
Accordingly, each of the driving members 4 and 7 is rotated counterclockwise by the urging force of each driving spring (not shown) and the urging force of each compression spring 6 and 9, and their mounting portions 4c and 7c
It comes into contact with the heads 5c, 8c of the iron piece members 5, 8 and stops.
FIG. 3 shows the state at that time, and the position shown in FIG. 3 is the exposure operation start position for each of the driving members 4 and 7.

In FIG. 3, the drive pins 4b, 7b of the respective drive members 4, 7 are still in contact with the holes 12a,
It does not touch the edge of 18a. This means that in the case of the present embodiment, in the setting operation, each blade group is configured to be stopped before each of the driving members 4 and 7 reaches the exposure operation start position. As can be seen from this, in this embodiment, when each of the driving members 4 and 7 operates from the position of FIG. 2 to the position of FIG.
Since each blade group is not operated at all, when the mounting portions 4c, 7c abut against the heads 5c, 8c of the iron piece members 5, 8, the influence of the inertia force of each blade group is completely reduced as in the conventional case. Without receiving, the impact force is reduced accordingly. Therefore, the suction holding force by the electromagnets 10 and 11 can be more reliably secured than before, and in other words, the power supply to the electromagnets 10 and 11 can be reduced.

After the state of FIG. 3 is obtained in this way,
First, the energization of the electromagnet 10 for the front blade is cut off, and after a predetermined time, the energization of the electromagnet 11 for the rear blade is cut off.
As a result, the leading blade drive member 4 and the trailing blade drive member 7 are rapidly rotated counterclockwise one after another by the urging force of the respective drive springs (not shown).
b and 7b push the respective arms 12 and 18 to cause each blade group to perform an exposure operation against the urging force of an arm spring (not shown), so that the slits formed by the two slit forming blades 17 and 23 form: The film surface is exposed.

The driving member 4 for the front blade, which has started the exposure operation first, stops when the driving pin 4b comes into contact with the buffer member 2 at the upper end of the long hole 1b, and the front blade group is also shown. Stops by contacting a stopper that does not exist. Therefore, in those stopped states, the four blades 14, 1 of the front blade group are set.
5, 16 and 17 are superimposed and stored at a position above the opening 1a. On the other hand, the rear blade drive member 7 that has started the exposure operation with a delay is the four blades 20, 21,
At the stage when 22 and 23 completely cover the opening 1a,
When the driving pin 7b is at the upper end of the elongated hole 1c,
And the rear blade group also stops by contacting a stopper (not shown). The state in which the exposure operation thus performed is completed is the state shown in FIG. 1. At this time, the opening 1a has the four blades 20, 21, 22, 22 in the developed state. 23.

In the above embodiment, the case where the arm springs (not shown) are hooked on the arms 13 and 19 has been described. However, their arms 13,1
It is known that a spring which is conventionally referred to as a backlash spring is applied to the spring 9. The backlash spring is originally
The arm 13 or 19 may be urged in either operation direction, and the urging force is not so large. Therefore, in the case of the configuration as in the present embodiment, it can be said that the arm spring also has such a function of the backlash spring. In other words, with the configuration as in the present embodiment, the number of components does not increase even if the arm spring is provided. However, the present invention is not limited to such a configuration.
It does not prevent multiplying by 2,18.

In the above embodiment, the shutter base plate 1 is provided with the stoppers 1j and 1k. However, recently, the shutter base plate 1 may be made of a synthetic resin material. If 1j and 1k are also integrally formed at the same time, it is advantageous in terms of cost. And, if it is manufactured in such a manner, in the case of the configuration of the present embodiment, the number of components does not increase by one compared with the conventional shutter configuration. On the other hand, since the shutter is made of many small parts, it is difficult to manufacture each product uniformly, and individual differences will inevitably appear. For this reason, various adjustment operations are performed in the manufacturing process. In the case of the above embodiment, when the stoppers 1j and 1k are eccentric pins, the stop position of the set operation of each blade group can be adjusted, which is preferable. Configuration.

Further, the urging force of the arm spring of the present invention works against the exposure operation of each blade group. Therefore, from the viewpoint of increasing the speed of the shutter, it is desirable to set the necessary minimum urging force. However, when doing so, at the time of the set operation, when each blade group operates following the drive pins 4b, 7b of each drive member 4, 7, unintended factors and individual differences of each blade group overlap. Occasionally, the operation may not start smoothly. However, in the case of the above embodiment, even if such a situation occurs, each drive pin 4b, 7b is
Momentarily press the edge of the set operation direction side of 2a, 18a,
It is designed to prompt the start of operation. Therefore, when such consideration is not required, the portion following the drive pins 4b and 7b does not need to be a hole as in the embodiment. In the above-described embodiment, the present invention is applied to both the leading blade system and the trailing blade system, and does not prevent application to only one of them.

[0035]

As described above, according to the focal plane shutter of the present invention, the setting operation of the blade group is not performed in conjunction with the end of the setting operation of the driving member as in the prior art. Prior to the exposure operation, when the driving member reaches the exposure operation start position from the set position, the inertial force of the blade group acts as a force for separating the iron piece member attracted to the electromagnet from the electromagnet, as in the related art. In addition, it is possible to reliably obtain the holding power of the electromagnet with low power consumption.

[Brief description of the drawings]

FIG. 1 is a plan view of an example showing an approximately half of a left side when viewed from a subject side, showing a state immediately after an exposure operation is completed.

FIG. 2 is a plan view of the embodiment shown in the same manner as FIG. 1, showing a set completed state.

FIG. 3 is a plan view of the embodiment shown in the same manner as FIG. 1 and shows a state immediately after the release operation and immediately before the start of an exposure operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Opening 1b, 1c Slot 1d, 1e, 1f, 1g, 1h, 1i Shaft 1j, 1k Stopper 2, 3 Buffer member 4 Driving member for leading blade 4a, 7a Pushed portion 4b, 7b Drive pin 4c, 7c Mounting part 5, 8 Iron piece member 5a, 8a Iron piece part 5b, 8b Shaft part 5c, 8c Head 6,9 Compression spring 7 Rear blade drive member 10 Front blade electromagnet 11 Rear blade electromagnet 12,13, 18, 19 arm 12a, 13a, 18a, 19a hole 14, 15, 16, 17, 20, 21, 22, 23 blade

Claims (3)

[Claims] An iron piece member attracted and held by an electromagnet is attached. When the set operation is performed, the iron piece member is attracted to the electromagnet by operating against the urging force of a drive spring to a set position beyond an exposure operation start position and photographing. A driving member which starts to be exposed by the urging force of the driving spring when the electromagnet is stopped and then stops after being operated to the exposure operation start position after being held, a plurality of arms pivotally attached to the main plate, and the like. A plurality of blades pivotally supported by the driving member, and the exposure operation is performed by the driving member; and a blade group having a lower urging force than the driving spring and being hung on the arm. An arm spring that is biased in the set operation direction, the arm spring being provided on the main plate, and the drive member reaching the exposure operation start position at least during the set operation, A focal plane shutter for a camera, comprising: a stopper configured to stop the operation of the blade group by an urging force of an arm spring. 2. A driving pin provided on the driving member,
2. The blade member is loosely fitted in a hole formed in one of the arms of the blade group, and the driving member can start the operation of the blade group during a set operation. 2. A focal plane shutter for a camera according to claim 1. 3. The focal plane shutter for a camera according to claim 1, wherein the stopper is an eccentric pin.